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Environment and Abundance; Biomes. Conditions. An abiotic factor that influences the immediate survival of an organism – temperature, humidity, pH, salinity, wind velocity, current flow, soil, pollutants, etc. Law of the Minimum.
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Conditions • An abiotic factor that influences the immediate survival of an organism – temperature, humidity, pH, salinity, wind velocity, current flow, soil, pollutants, etc.
Law of the Minimum • The distribution of a species will be controlled by that environmental factor for which the organism has the narrowest range of adaptability or control. - Carl Sprengel 1828
Liebig’s Law of the Minimum - 1840 Or – the nutrient in lowest supply will set the limit to plant growth
Distribution • Is there a relationship between geographic range (distribution) and population size?
Rule of thumb: The range of the average species corresponds to the range of the average graduate student. University of Connecticut Ecology Grad Students
south south north
Range size and abundance Ecologists have long suspected that a species that is widespread in its distribution may tend to be more common or abundant in its population size What causes such patterns? 1. sampling error 2. ecological specialization 3. local population model
Sampling Errors – Rare SpeciesKnotroot bristlegrass and peregrine falcon
Climate and distribution • Climate, particularly temperature and precipitation, influences the distribution of the earth's terrestrial organisms • In each major kind of climate, a distinctive type of vegetation develops - for desert plants occur in arid (dry) climates, grasses with semi-arid climates and forests with moist climates • Certain animals, fungi and other organisms are associated with particular vegetation types
Biomes • A Biome is a large, relatively distinct terrestrial ecosystem characterized by particular climate, soil, plants and animals, regardless of where it occurs on earth • A biome's boundaries are determined by climate more than by any other factor
Tundra • Tundra occurs in extreme northern latitudes where the snow melts seasonally (southern hemisphere has no equivalent) • Tundra has long, harsh winters and very short summers - growing season is 50 to 160 days depending on location – summer days are long • Tundra soils are young - formed after last ice age, nutrient poor, little organic matter - have permafrost - permanently frozen layer of soil • Plants mostly less than 30 cm tall – mosses, lichens, sedges, grasses • Animals – weasels, foxes, snowshoe hares, ptarmigan, caribou, mosquitoes, blackflies
Taiga • Taiga - evergreen forests of the north • Taiga is found in northern America, Asia and Europe - covers 11% of land • Winters cold and severe - growing season longer than tundra - greater than 160 days - little precipitation, about 50 cm (20 inches) per year • Soil is acidic, mineral-poor, deep layer of poorly decomposed pine and spruce needles at surface • Numerous lakes and ponds • Plants – aspen, birch, but spruce and fir dominate • Animals – caribou, wolves, bears, moose, rodents, rabbits, lynx, sable, many migratory birds, many insects
Temperate rain forests • Occurs on northwest coast of North America, southwestern Australia, southern South America, nothern Japan • very high precipitation - 200 to 380 cm (80 to 152 inches), much condensation from coastal fogs - little seasonal temperature variation - winters mild and summers cool • Nutrient poor soil, but may have high organic content • Plants – evergreen trees – western hemlock, Douglas-fir, Sitka spruce, western red cedar, many epiphytes – mosses, lichens, ferns • Animals – squirrels, deer and numerous birds
Temperate deciduous forests • Occur where temperate zone precipitation ranges from 75 to 125 cm (30 to 50 inches) • Typically have hot summers and cold winters • soil has rich topsoil with much organic matter, deep clay-rich lower layer • In US dominant plants are broad-leaved trees – oaks, hickory, beech maple – in south broad-leaved evergreens – live oak, magnolia • Animals – deer, bear, wolves, cougars, rodents, many birds, many reptiles and amphibians
Temperate grasslands • Occur where annual precipitation is 25 to 75 cm (10 to 30 inches) • Summers hot, winters cold, rainfall is often sporadic • soil is rich in organic matter, minerals build up in top layer of soil, dead organic matter from annual die-back of grasses builds up soil organics, grass roots may form turf or sod • shortgrass prairies may be called steppes, more rainfall than deserts but not much - 10 to 15 inches • Plants – grasses dominate – tallgrasses where wetter, shortgrasses where drier – trees only along rivers • Animals – bison, antelope, wolves, coyotes, prairie dogs, ferrets, birds of prey, grouse, reptiles, many insects
Mediterranean ecosystems • Mediterranean - thickets of evergreen shrubs and small trees • some temperate areas have climates with mild winters with abundant rainfall and very dry summers - called Mediterranean climates - occur around Mediterranean, California, western Australia, Chile, South Africa • In California we call this ecosystem chaparral - soil is very thin and nutrient poor • Fires are common, frequent in late summer, early autumn • plants usually dense growth of evergreen shrubs, but may have short scrubby pines and oaks - often have sclerophyllous leaves - hard, small, leathery leaves that resist water loss • Animals – mule deer, wood rats, chipmunks, lizards, many songbirds, other birds
Deserts • Deserts are very dry habitats of both temperate and tropical zones - low water content of the desert atmosphere leads to wide daily temperature range • deserts vary greatly depending upon amount of precipitation - usually less than 25 cm (10 inches) per year • desert soil poor in organics, rich in minerals • some deserts so dry have virtually no plant life - Namib and Atacama desert • Plant cover sparse, much soil exposed – perennial and annual or ephemeral plants – in North America – cacti, yucca, Joshua trees, bunchgrass • Animals – small – rodents, lizards, tortoises, snakes, birds, insects
Tropical savanna • Savannas are a tropical grassland which typically have widely scattered trees • either low rainfall or seasonal rainfall with prolonged dry periods - often 85 to 150 cm (34 to 60 inches) • Temperature doesn't change much - often in 80's or 90's • Savanna soil is low in mineral nutrients • Tropical savanna found in Africa, South America and northern Australia • Plants – grasses, acacia trees – adapted to survive or recover quickly from fire • Animals – huge herds of hoofed mammals in Africa – many predators – lion, leopard, hyena, wild dog
Tropical rainforest • Tropical rain forest occurs where temperatures are high throughout the year and precipitation occurs almost daily - annual precipitation may be 200 to 450 cm (80 to 180 inches) - much of the rainfall is locally recycled as water that enters atmosphere from transpiration quickly falls out again • Soil is usually very old and nutrient poor, low in minerals and organics - decomposition and recycling is very quick due to high temperature and high availability of water • extremely diverse forests - trees, lianas – evergreen flowering trees • Animals – very diverse insects, reptiles, amphibians, birds, monkeys, sloths
Will my prairie ecosystem change from this to this? Illinois tallgrass prairie East Texas Piney Woods
Or something entirely different? Dan Janzen has predicted that with increasingly human dominated ecosystems, global climate change and the spread of cosmopolitan non-native species, the entire world will become ecologically uniform.
